This invention relates to the water distribution system in a dishwasher, particularly a dishwasher in which there is a lower level water distribution assembly which is separate from but is operated in cooperation with rotation of the lower assembly wash arm.
Prior art patents which disclose dishwasher water distribution systems having rotating wash arms with several levels of distribution are seen in the following United States patents: T. F. Zurek U.S. Pat. No. 3,009,470; J. D. Warhus U.S. Pat. No. 3,064,664; L. J. Martiniak U.S. Pat. Nos. 3,064,665 and 3,213,866; H. Jordan et al U.S. Pat. No. 3,288,156; D. S. Cushing et al U.S. Pat. No. 3,841,342; C. I. Platt et al U.S. Pat. No. 3,918,644; R. W. Spiegel U.S. Pat. No. 3,941,139; W. W. Jarvis, Jr. et al U.S. Pat. No. 3,951,683; P. J. La Prod et al U.S. Pat. No. 3,951,684; and T. E. Jenkins et al U.S. Pat. No. 3,969,137. The patents to Zurek, Warhus, Jordan et al, Cushing et al, Jarvis et al, La Prod et al, and Jenkins et al teach a rotating lower wash arm and a portion of the lower assembly is constructed to lift under water pressure to engage and operate an upper unit. The Martiniak patents teach a lower wash arm assembly which rises and via an elastic or rubber coupling operatively engages the upper conduit or tower. The hub of the wash arm is made from several parts and is joined to the wash arm subassembly. The skirt of the hub fits inside the lower distributor sleeve. The Platt et al patent teaches several wash arms at different levels on a distributor conduit and the upper wash arm is removable and reversible to obtain different water spray patterns.
The Jenkins et al U.S. Pat. No. 3,969,137 teaches a non shiftable wash arm, and has a form of stabilizer tension spring interior of the wash arm assembly.
As evidenced by the above noted prior art patents, many of the previously known dishwashers have a lower wash arm assembly and an upper wash tower and a pump receiving and recirculating water from a tub sump through the lower wash arm assembly and also to an upper rotatable wash arm or tower.
In many such prior art dishwashers, a portion of the water enters the lower wash arm which rotates on a lower distributor upon a bearing and is locked to the lower distributor by means of a rotating lockring. The remainder of the water continues upward through a bushing and into an upper distributor riser which telescopes or expands upward under the water pressure and engages a gasket fastened on the base of a rotatable tower. This entire assembly above the lower distributor and bearing rotates as a unit and is driven by means of reaction water jets. However improved dishwasher systems are being developed with pumps generating a higher head of pressure than used in prior systems, and such higher heads create difficulties in proper rotation of the washer distribution units.
In the present invention water under pressure enters the lower wash arm hub assembly which includes a combined lower and upper distributor and wash arm support structure. Water pressure causes the entire wash arm and distributor assembly to lift and engage the tower, being guided in the upward movement by a bearing pin fixed to inlet structure and about which the entire assembly will rotate. The construction of the present invention will function in a highly satisfactory manner under a variety of pump pressures.